• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.139-143
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• 1996

The theoretical study of deformation behavior for continous extrusion process (CONFORM) is shown in this paper. The extrusion process is compared with a conventional route, side extrusion, considering extrusion ratios, flash gaps and coefficients of friction. In each case the distribution of strain and strain rate is predicted by using the finite element method. In this study simplifying assumptions on the deformation geometry are made to investigate the plastic flow occuring in the area of deformation of the Conform process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.232-235
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• 1995

A side-extrusion model, meant for deeper understanding of the material flow in the CONFORM (continuous extrusion forming) of trub shaped aluminum profiles is presented. In order to get the desirded straight shape of the extrudate,every part of its cross-section must exit the die with the same velocity. Problem is assumed by plane strain UBET-model to analyze it in a simplified way. This has been done by studying the side-extrusion through a two -hole die face. The flow is balanced by determining the optimum lengths of the bearing lands, i.e., those lengths which result in equal exit velocities of the extrudates. Furthermore, the material flow, as influenced by the punch velocity, has been investigated.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.116-121
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• 1999

Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.174-181
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• 2001

An upper bound elemental technique(UBET) has been carried out to predict the forming load, the deformation pattern and the extrude length of the lateral extrusion of a spider for the automotive universal joint. For the upper bound analysis, a kinematically admissible velocity field(KAVF) is proposed. From the proposed velocity field, the upper bound load, the deformation pattern and the average length of the extruded billets are determined by minimizing the total energy consumption rate which is a function of unknown velocities at each element. Experiments are carried out with antimony-lead billets at room temperature using the rectangular shape punch. The theoretical prediction of the forming load, the deformation pattern and the extruded length are good in agreement with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1129-1133
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• 2001

An upper bound elemental technique(UBET) has been carried out to predict the forming load, the deformation pattern and the extruded length of the lateral extrusion of a spider for the automotive universal joint. For the upper bound analysis, a kinematically admissible velocity field(KAVF) is proposed. From the proposed velocity field, the upper bound load, the deformation pattern and the average length of the extruded billets are determined by minimizing the total energy consumption rate which is a function of unknown velocities at each element. Experiments are carried out with antimony-lead billets at room temperature using the rectangular shaped punch. The theoretical prediction of the forming load, the deformation pattern and the extruded length are good in agreement with the experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.49-54
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• 2010

Rotor pole for AC(alternating current) generator is manufactured through transfer warm forging die. As soon as the material is heated at the warm manufacturing process, it is transferred to the first stage for upsetting work and then to the second stage for lateral extrusion work. The processes at the lateral extrusion work such as die block, die bushing, center punch, and side punch make severe condition and abrasion which leads to shorten the die life. This causes production decrease, long maintenance time, and low level of precision. Research on the die material selection, heat process cycle improvement, electric discharge machining trouble solution, and re-construction of main parts is expected to find a method to lengthen the die life up to 40 - 50%.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.54-61
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• 1997

Furthermore the rothor pole, with a solid type, manufactured by cold forging process at present should dmploy 3 press lines which consist of total 7 processes. Since A.S.B. treatment is prerequisite for the press line, the 3 times of A.S.B. treatment requires a long lead time, with little contribution to the reduction in cost. The author has investigated, through this researach, the possibility of a new forging method for a rotor pole production with (1) 2 pass instead of 3 press lines (2) only one A.S.B. treatment instead of 3 ones (3) solid type instead of sectional type, and (4) improvment of material property during process using a modified forging process and a specially designed die.

• Journal of the Korean Geotechnical Society
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• v.17 no.1
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• pp.99-107
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• 2001

일반적으로 샌드파일 설치로 인해 파일주변지반은 교란되어 스미어 영향과 배수저항에 의해 압밀지연 현상이 발생하는 것으로 알려져 있다. 특히 예민한 점성토 지반일 경우 교란정도가 크며, 틱소트로피현상이 지연될 경우 지지력 및 압축특성은 불리하게 된다. 본 연구에서는 원지반 특성이 파악된 채취시료를 이용하여 완전 교란조건에서의 실내모형시험과, 염분농도변화에 의한 실내역학시험을 실시하였다. 실내모형시험 결과 낮은 하중단계에서의 압밀계수는 비교란 시료의 특성과 유사하게 나타났으며, 염분농도 증가에 따라 일축압출강도가 증가하고 강도회복은 빠르며 압축지수는 작게 나타났다. 결과적으로 점성토지반 간극수중 염분농도는 강도증대와 압축특성 변화에 영향을 주며, 틱소트로피 증대의 영향요소가 적은 담수지반에서 샌드파일을 시공할 경우 발생하는 과다침하의 한 원인으로 여겨지는바, 이와 같은 요인은 측방유동에 의한 침하거동과 함께 고려하여야 할 영향요소로 파악되어야 할 것으로 판단된다.